The IPCA said the officer's actions in taking the woman to the ground were an unnecessary use of force.
A police spokesperson told Newshub the man was arrested a short time later.
Police have confirmed a vehicle found burnt out on the island belonged to the man.
A post-mortem has been completed, and police are treating the man's death as "unexplained".
A homicide investigation is ongoing.
Officers were called to a property on Orchard Street where a man was found with critical injuries.
Now, 10 years later, he has gone full circle, recently joining the New Zealand Police Force himself.
Eagle-eyed firearms enthusiasts saw something amiss with a revolver-type pistol.
Inspector Chris Wallace called it a true test of honesty.